net/mlx4: fix Rx after mbuf alloc failure

net/mlx4: fix Rx after mbuf alloc failure

Fixes issue where mlx4 driver stops receiving packets when mbuf
allocation fails in mlx4_rx_burst().

This issue appears to be caused because the code doesn't recycle the
existing mbuf to the sges array when mbuf allocation fails as is done
in the code right above it which handles (wc.status != IBV_WC_SUCCESS).

Copying the code from the above case fixes the issue.

Fixes: acac55f16412 ("mlx4: use MOFED 3.0 fast verbs interface for Rx operations")
Cc: stable@dpdk.org
Signed-off-by: Charles Myers <charles.myers@spirent.com>
Acked-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>